NBA Jam issue

jcterzin

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Hello-

I have this NBA jam board that I had working but with miscolored graphics. I figured it was a dirty rom problem so I took off about half of the roms and thoroughly cleaned them. I reinserted them in the board and tried plugging it back into the cab but now I get nothing when I power up. I made sure they were in securely and tried again with no change. What is going on here? I'm using a gretzky cab to test the board, if that makes a difference...
 
How did you clean the ROMs?

Did you plug them back into the correct location? Did you put them in the right way? Did you fold any legs under or miss a leg into a socket?

I have found and created these problems enough to know that it is REALLY easy to do. Now I double-check all chip orientation and legs under BRIGHT LIGHT. And still end up with the above problems! :)
 
once you check what majorhavoc said, and make sure you don't have a bunch of shoddy wire hacks ( loose connections, electrical tape, odd splices).

then check your psu both to make sure it's working and to check to make sure the voltages are within tolerance.
 
Did you install the chips with the board still inside the the cab?
I wondering if the board got bent to the point that a trace was broken?

I say remove the board and looks at it in the bright sun to look for bent leads or anything that not in the right place..
 
just throwing this out there, since it's a common problem from these changing hands so much since the days of commercial operation...

the pins on the through-hole soldered components on the T-unit boards are generally long enough to get bent and touch nearby stuff if the board was set completely flat (meaning the mounting feet were removed) and can short out whatever. I go over them with electric shears, and if they're bent over enough to where you can't cut them without butchering your board, use a small precision flathead to bend them back upright, then cut.

the PLCC sockets (the brown sockets for CPU-ish chips) also have a tendency to crack in the corners, meaning the walls of the sockets don't make good enough contact against the chips.

if your game roms (the ones furthest to the left offset from the rest) have corrosion on the chip legs, use sandpaper on them to make them shiny and good looking again, then reseat those. you also have to make note that you don't reinstall the ROMs backwards, the chips themselves have a U-shaped notch just like the socket, they have to face the same way. if you plugged them in backwards then your roms are toast.

additionally, if the cabinet has the original power supply in it, chances are that could be on its way out too, hence the black screen. I've seen this condition several times on my KI cab before I replaced the power supply. power supply goes into overcurrent protection shutdown, and it's usually caused by the +5 adjustment pot being corroded. you can salvage these in many cases, but you have to turn the knob completely back and forth both ways several times to "clean" it... but doing this, you won't know what the voltage setting will be at when you run it again. you can run the power supply with the JAMMA harness unplugged, but you can't do it for too long, or else you'll burn up a switching power supply. this can happen in as little as 10 seconds, so you'd have to be quick about setting it to about 5.10 before you plug the JAMMA harness back in and fine tune it.

all else fails, you may just have a bad board. that's the nature of the beast.
 
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